A)surface area of sphere is 4 pi r^2
b)just imagine creating small squares all over the sphere.and connect the corners of all squares to the center of the sphere.
c)they now become a square pyramid.
d) volume with any base is Bh/3
e) perpendicular height is radius of the spheres like here.
f)hence,volume of the sphere=1/3*S.A*h
=4/3 pi r^3
hope this helps u....